In a small bowl, combine the oil and Creole seasoning. Mix well. Spread each side of the steaks completely with the Creole seasoning mixture. Place in a shallow pan, cover with plastic wrap and refrigerate for at least 4 hours. Remove and bring to room temperature before grilling, about 30 minutes.

Preheat the grill. In a saucepan, over medium heat, melt the butter. Add the shallots and garlic. Season with salt and pepper. Sauté for 1 minute. Add the red wine and bring to a boil. Reduce the heat to medium and stir in the demi-glace. Simmer for 2 minutes and remove from the heat, keeping warm. Place the steaks on the grill and cook for about 4 to 6 minutes on each side for medium-rare. Remove from the grill and cool for a couple of minutes before serving. Place the steaks and potatoes on each serving plate. Spoon a quarter of the sauce over each steak. Garnish with parsley.